Frank Moerman - Articles and news items

Vacuum allows processes to be performed that cannot otherwise be done under atmospheric conditions. Moreover, it offers a huge advantage in the processing of heat and oxygen sensitive materials. There are numerous applications in the food industry that rely on vacuum. The vacuum required in the food industry extends in the range of 1-600 mbar vacuum absolute (vacuum pressure measured relative to absolute perfect zero vacuum), and is applied in the transport, processing, filling and packaging of foodstuffs, in cleaning operations and in the creation of appropriate hygienic conditions.

‘Sous-vide’ is the French word for ‘cooking under vacuum’. This cooking method aims to maintain the integrity of ingredients by heating them for an extended period (usually 8 – 10 hours, sometimes well over 24 hours) at relatively low temperatures (usually between 60-70°C) and pressures of 50 – 250 mbar absolute (40 – 60 mbar lower than the vapour pressure of water at a given temperature, Figure 1, page 68. But, there are cooks that prepare food ‘sous vide’ at temperatures as low as 55°C. However, for food safety reasons, that practice is not really recommended. After vacuum cooking, the food should be held at 55°C or above until served for immediate consumption, or should be rapidly cooled to below 3.3°C. A water ring pump is used to produce the absolute vacuum pressures required.

In part 2 of his article examining the selection of spraying systems, Frank Moerman gives an overview of the different rotary jet heads offered for sale on the world market. The article finishes with details on the positioning of the tank cleaning machine in the reactor/tank.

Rotary jet heads are fluid driven (turbine-type or piston-type) or motor-driven (electric or pneumatic) tank washing nozzles. They are composed of a stator, a drive mechanism and a rotary washing head with between one and four or more nozzles. At high pressures, solid streams of 7-30 m in stationary conditions and 4-20 m at rotation are obtained. Turbine-type rotary jet heads can operate at pressures of 3-250 bar, while piston-type rotary jet heads operate at 3-12 bar. Rotary jet heads are made of stainless steel 316 or 316L, operating at temperatures of -30°C to +120°C (with a maximum of 140°C).

In the beverage processing industry (spirits, brewing, juice bottling, dairy, etc.), cleaning-in-place is a well established technique. On a daily basis, huge numbers of small and large vessels must be cleaned in an economical, efficient and reproducible manner. To achieve these objectives, tank cleaning machines are used. In part 1 of his article, Frank Moerman compares the various static and rotary spraying heads offered for sale on the world market.

Cleaning-in-place is a method where cleaning of complete items of plant equipment or pipeline circuits is automatically performed without dismantling or opening the equipment. Little or no manual work on the part of the operator is involved. The process involves the circulation of cleaning solutions (detergent and cleaning solutions) through tanks and piping within the processing plant and the jetting or spraying of surfaces under conditions of increased turbulence and flow velocity. Cleaning-in-place is based on the application of a certain amount of energy – enough to ensure that the equipment surface is clean. This energy is provided by the solution temperature (thermal energy); the use of detergent or solvent (chemical energy) and the application of suitable pipeline velocities or pressures (kinetic energy).